If he's up to it, maybe he could try some Elektron stuff? The learning curve is what it is, and it surely isn't cheap, but there's usually a lot of power under the hood. If he's looking for something more aproachable and slightly cheaper, Korg Minilogue is a way to go. Middle road would probably be something like OP-1.so our vocalist is looking to add a small key/synth/sampler rig. mainly just for intros/outros and jam sections, not something that he would be playing the entire time. hopefully something small with a budget under $1,000 or less.